These small insects are also called plant lice; there are various species, which generally differ in color. Some species particularly prefer some plants, such as the golden oleander aphid. Aphids parasitize most ornamental plants, and also horticultural and fruit plants; they nest on the most tender buds and around floral buds; their mouth is specialized to break the outer wall of the most tender stems and to suck the sap of the plant. The result is often a general weakening of the whole plant, the curl of the leaves, the stunted development of flowers and fruits. Often from the large colonies of aphids runs a sticky substance, called honeydew, formed by the sugars present in the sap of the plants; this substance is sometimes colonized by dark mushrooms, called fumaggini.
Often then near the aphid colonies there are colonies of ants, which collect the honeydew from the aphid's abdomen, to use it as nourishment; the ants move the young aphids from one plant to another, to widen their colonies, as if they were raising them.
Aphids develop particularly when the climate is humid and cool, so especially during spring, and spent even during the autumn; in houseplants they can develop throughout the year. Each new population has a very rapid development, it is therefore essential to intervene when the first specimens are noticed, checking the young shoots.

Fight the aphid

Traditionally the fight against aphids is practiced using pyrethroids or nicotinoids, insecticides with a wide spectrum of action, harmful both for aphids and for useful insects. Pyrethrum insecticides are also widely used, even in this case it is a broad spectrum insecticide, but if we try to use pyrethrum in the evening, and when the plants are not yet in bloom, we will at least avoid damaging the bees and other pollinating insects.
Our grandmothers used nicotine macerate against aphids, prepared by letting a couple of cigarettes soak in water for a few days; this product was considered as not harmful, as it is natural and not synthetic; in reality, even tobacco macerate is a very powerful and broad-spectrum insecticide, which damages all insects in the garden and in the garden.

Aphids: the bio struggle

The problem of aphids is very much felt, both by hobbist gardeners and by farmers; a large infestation of aphids can quickly ruin the crops of an entire field.
In hobby, we often notice how the simple removal of aphids from the plant discourages their reappearance; for this purpose, water added with flakes of Marseille soap is used; this solution, besides detaching the aphids from the foliage, tends for a few days to avoid its reappearance. On the market it is also possible to find the so-called soft soap, which contains potassium instead of sodium, much less harmful to the foliage.
If instead the infestation is already wide and therefore we wish to kill the aphids, in addition to removing them, we can prepare a macerated with nettle leaves, to vaporize on all the foliage of the infested plants; nettle macerate can also be found on the market as a concentrate to be diluted in water.
As far as the garden and large crops are concerned, aphids can also be defeated by promoting or encouraging the spread of useful species, such as ladybirds, whose larvae feed on aphids, or like some species of Hymenoptera, which deposit their eggs at inside the body of the aphids, devastating even very numerous populations. Even the small red spider mites (not the harmful mites, but the small red spiders of visible size) feed on the aphids, containing their population.